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WO2009059693A1 - Interféromètre de linnik compact - Google Patents

Interféromètre de linnik compact Download PDF

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Publication number
WO2009059693A1
WO2009059693A1 PCT/EP2008/008906 EP2008008906W WO2009059693A1 WO 2009059693 A1 WO2009059693 A1 WO 2009059693A1 EP 2008008906 W EP2008008906 W EP 2008008906W WO 2009059693 A1 WO2009059693 A1 WO 2009059693A1
Authority
WO
WIPO (PCT)
Prior art keywords
interferometer according
side lens
beam splitter
prisms
interferometer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2008/008906
Other languages
German (de)
English (en)
Inventor
Peter Lehmann
Jan Niehues
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Carl Mahr Holding GmbH
Original Assignee
Carl Mahr Holding GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carl Mahr Holding GmbH filed Critical Carl Mahr Holding GmbH
Publication of WO2009059693A1 publication Critical patent/WO2009059693A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/02075—Reduction or prevention of errors; Testing; Calibration of particular errors
    • G01B9/02076—Caused by motion
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02049—Interferometers characterised by particular mechanical design details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/04—Measuring microscopes

Definitions

  • the invention relates to a Linnik interferometer for metrological applications.
  • interferometric measuring devices are preferably used on account of the high achievable measuring accuracies.
  • phase-shifting interferometry or deep-scanning white light interferometry used.
  • the latter is known, for example, from DE 10 2004 025 290 A1.
  • phase-shifting interferometry can be deduced, for example, from DE 102 56 273 B3.
  • Michelson interferometers are suitable for quantitative interference microscopy.
  • a beam splitter which is inclined by 45 °, is located between an object-side microscope objective and the object to be measured, which splits the incident light into a measuring beam and a reference beam. Due to the spatial extent of the
  • Beam splitter are the remaining working distance and the maximum achievable numerical aperture low, so that Michelson interferometer in conjunction with low magnifications (maximum 5X magnification) are used.
  • a beam splitter plate and a reference mirror are located in the optical beam path between the actual object and the measurement object. This arrangement is characterized by compactness out. However, a part of the working distance in front of the lens is also claimed by the jet engine and the reference mirror.
  • Mirau interferometers are therefore preferably used in the range of medium magnifications (10 times to 50 times) and average numerical apertures (0.3 to 0.55).
  • Linnik interferometers are typically realized by means of an equilateral beam splitter cube in which the beam splitter surface is inclined by 45 ° to the optical beam path.
  • the two optical axes of the four optically active surfaces of the beam splitter cube which are offset by 90 ° from one another are the two 90 ° offset lenses, the light source with the illumination optics and the imaging beam path optionally with a tube lens, an observation device e.g. in the form of a camera and / or an eyepiece.
  • the Linnik lens has the advantage that the entire working distance of the microscope objective is free and available, so that all known from the light microscopy combinations of working distance and numerical aperture of the lens can be realized.
  • very large working distances of over 5 mm at numerical apertures of more than 0.5 and at low working distances numerical apertures greater than 0.7 and thus high lateral resolutions can be achieved.
  • this arrangement has the disadvantage that it must be accessible from three sides in order to adjust the reference mirror, the light source and the camera or another observation device.
  • the star-shaped spatial arrangement has a disturbing effect due to its large size. This applies in particular if such an interferometer is to be integrated, for example, in a measuring and positioning system such as, for example, in a coordinate measuring device.
  • corresponding Linnik interferometers have proved to be susceptible to vibration, especially at large working distances, which makes industrial use more difficult.
  • Linnik interferometer should be designed so that it has the least possible spatial expansion and is robust and compact.
  • the Linnik interferometer is of modular design and flexible in its arrangement, whereby both the use of objectives with a large working distance and the use of high-aperture objectives with a short working distance should be possible.
  • the Linnik interferometer has a measuring-object-side objective, a reference-mirror-side objective, a reference mirror, a lighting device and an observation device, for example in the form of a camera and / or an eyepiece.
  • a beam divider arrangement connects these elements with each other.
  • the observation device, the Lighting device, the reference mirror side lens and the reference mirror arranged on one and the same side of the beam splitter assembly. This results in a compact, robust and vibration-insensitive construction.
  • Such an interferometer is particularly suitable for use in measuring machines as a measuring head.
  • the illumination device, the observation device and the reference mirror-side lens are arranged on one side of the measuring head.
  • the measuring head thus builds slim and compact.
  • the access to the individual elements, in particular the reference-mirror-side lens, the reference mirror, the light source and the camera is very good. All of these elements are located on one side of the interferometer. Adjustment work, such as the adjustment of the reference mirror, the light source and the camera can thus be carried out very easily and in a clear manner.
  • the system proves to be very less susceptible to vibration at long working distances, i. large distances between obj ekt Schemeen objective and measurement object or between the reference mirror side lens and reference mirror.
  • Such large working distances have hitherto often led to difficulties with regard to the vibration susceptibility.
  • the reduction in susceptibility to vibration allows an increase in the measuring speed.
  • the reference mirror-side objective, the observation device and the illumination device each define an optical axis, wherein these optical axes are preferably arranged in a common plane. Further preferably, these optical axes are oriented parallel to each other.
  • the structure is correspondingly clear and robust.
  • the object-side lens also has an optical axis. This can lie with the other optical axes in a common plane or be oriented at a different angle. For example, this can be a right angle.
  • the optical axis of the object-side lens is thus perpendicular to the above-mentioned plane. This may correspond to a fixed setting.
  • the optical axis of the object-side lens may also be possible to bring the optical axis of the object-side lens against the above-mentioned plane by appropriate adjustment in various settings. This is achieved in an embodiment in which the object-side lens is connected via a pivotally mounted prism to the rest of the beam splitter assembly.
  • the beam splitter arrangement preferably has at least two beam splitter prisms. These are preferably as isosceles 90 ° prisms, i. formed by isosceles, right-angled triangular surfaces each with two Kathe- tenflachen and one hypotenuse area.
  • the two triangular prisms abut one another with a catheter surface and thereby define a beam divider plane.
  • the remaining elements of the interferometer are connected to the hypotenuse surfaces of these beam splitter prisms.
  • one of the beam splitter prisms or both may be subdivided perpendicular to the hypotenuse into subprisms.
  • individual elements for example the object-side objective, can be pivotably connected to the beam splitter arrangement about an optical axis.
  • the reference mirror-side lens and the reference mirror form a structural unit. This is particularly advantageous if a lens change is provided. Then, the object-side lens and the reference-mirror-side lens can be easily exchanged at the same time, for example, to set another aperture or magnification. Access to the reference mirror-side lens is then particularly easy.
  • FIG. 1 shows a measuring head of a measuring machine with the interferometer according to the invention in a perspective, schematic view
  • FIG. 2 shows the interferometer of the measuring head according to FIG. 1, in a schematic functional representation
  • FIG. 3 shows a modified embodiment of an interferometer according to the invention, in a schematic plan view
  • Fig. 4 shows the interferometer of Figure 3, in a schematic side view
  • FIG. 1 illustrates an arm 1 of a measuring machine, which carries a measuring head 2 at its free end and is freely positionable in space, in at least one, preferably several directions.
  • the measuring head 2 is used to measure a measuring object 3, for example a workpiece.
  • the measuring head 2 is constructed as a Linnik interferometer 4, the beam path of Figure 2 shows. To him belong a lens 5, which faces the measuring object 3 and has an optical axis 7, an objective 8, which has an optical axis 9 and a reference mirror 10 faces.
  • the optical axes 7, 9 are perpendicular to each other and lie in this embodiment in a common plane.
  • the reference mirror 10 is oriented perpendicular to the optical axis 9 and adjustable by adjusting means, such as three adjusting screws 11, 12, 13, in its distance from the lens 8 as well as in its inclination.
  • the reference mirror 10 and the lens 8 form a structural unit 14, which is detachably connected to the measuring head 2.
  • the unit 14 is on one side of the measuring head 2, e.g. arranged accessible on its upper side 19.
  • the unit 14 is arranged on the same side as the measuring arm 1 and mounted on a support plate.
  • the Linnik interferometer 4 also includes an observer 15, e.g. in the form of a CCD camera 16, which may have a tube lens 17 or another optical element defining an optical axis 18 for the observation device 15.
  • the observation device 15 is preferably arranged on the same side 19 of the measuring head 2 as the unit 14.
  • the Linnik Interferometer 4 also includes a Lighting device 20 with a light source 21, for example in the form of an LED and an illumination optical system 22, which defines an optical axis 23.
  • the optical axes 9, 18, 23 are preferably oriented parallel to one another and arranged in a common plane, which is parallel to the plane of the drawing in FIG.
  • the unit 14, the observation device 15 and optionally also the illumination device 20 are preferably mounted together on the carrier plate and, if necessary, interchangeable.
  • the carrier plate is connected to the carrier arm 1 for reasons of vibration technology.
  • the objectives 6, 8, the observation device 15 and the illumination device 20 are connected to one another by a beam splitter arrangement 24, which preferably comprises at least two prisms 25, 26 coupled to one another. These are preferably constructed as isosceles triangle prisms.
  • the prism 25 has a hypotenuse surface 27 and two catheter surfaces 28, 29, which form a right angle with each other.
  • the prism 26 also has a hypotenuse surface 30 and two catheter surfaces 31, 32 that enclose a right angle with each other.
  • the catheter surfaces 29, 31 abut each other and form an interface at which the division into measuring beam and reference beam takes place.
  • the hypotenuse surface 27 is aligned perpendicular to the optical axis 7 of the objective 6.
  • the hypotenuse surface 30 is aligned perpendicular to the optical axis of the objective 8, which is directed to the reference mirror 10.
  • lenses which have been corrected to an infinite image width are used, so that the optical image is formed in the focal plane of a tube lens facing the objective.
  • the prisms 25, 26 are isosceles 90 ° prisms. These can be inexpensively Precision be made so that the path lengths in the glass from the Hypotenuse Chemistry 27 to the lens side surfaces formed by the Hypotenuse vom 27, 30 and back to the also formed by the Hypotenuse constitutional 30 light exit surface, which faces the observation device 15, to a sufficient extent to match. Dispersion effects are avoided, as they could result from the use of short-coherent light from different lengths of glass.
  • the illumination device 20 is connected to the hypotenuse surface 27, for example via a further prism 33.
  • This can also be formed as an isosceles 90 ° prism whose hypotenuse surface acts as a mirror.
  • the accuracy requirements for the prism 33, which serves to 90 ° deflection of the illumination beam path, are significantly lower.
  • the prism 33 can be omitted if the illumination device 20 is mounted perpendicular to the hypotenuse surface 27, so that its optical axis 23 is perpendicular to the Hypotenuse Structure 27.
  • the catheter surfaces 28, 32 can be formed mirrored to deflect the optical axes 7, 9 of the two lenses 6, 8 in each case by 90 °.
  • the deflected optical axes meet at a common point, in which the deflected optical axis 23 of the illumination device 20, such as the optical axis 18 of the observation device 15, enters.
  • the common point is at the interface between the catheter surfaces 29, 31.
  • the Linnik interferometer 4 described so far generates at the interface of the light beam of the illumination device 20, a reference beam which is guided by the prism 26 in the lens 8, is guided by this on the reference mirror 10 and back to the interface.
  • the other part of the light beam emanating from the illumination device 20 is led back at the interface to the catheter surface 28 and from there into the objective 6 and to the measurement object 3 and in the same way.
  • the measurement beam and the reference beam are reunited and guided along the optical axis 18 to the observation device 15.
  • the measuring beam and the reference beam can be superposed here in order to generate interference images which are recorded, evaluated or further processed by a connected evaluation device.
  • the lenses 6, 8 are preferably designed to be changeable. For example, they can be exchanged in pairs with appropriate changers or by hand. This becomes particularly simple when the objective 8 is linked to the reference mirror 10 and its adjustment mechanism to form a structural unit which is to be changed as a whole.
  • FIG. 3 to 5 illustrate a modified embodiment in the form of a Linnik interferometer 34.
  • elements are present that are structurally and / or functionally identical to the above-described elements of the Linnik interferometer 4, the already introduced reference symbols are still used. The above description applies accordingly based on the same.
  • the prism 25 is subdivided into two subprisms 25a, 25b along a surface 35.
  • the surface 35 is perpendicular to the hypotenuse surface 27.
  • the subprism 25a is at 90 ° to the surface
  • the optical axis 7 is perpendicular to a plane passing through the optical prism 25b Axes 9, 18, 23 is fixed.
  • the prism 26 ' may be undivided or, as shown in FIG. 3, likewise divided, its dividing surface 36 then being at right angles to the hypotenuse surface 30.
  • Figure 5 illustrates the arrangements in front view. In another embodiment, it may be provided to pivot the prism 25a against the remainder of the beam splitter assembly 24 'thereby to make the angle ⁇ variable at which the optical axis 7 intersects the plane defined by the remaining optical axes.
  • Interferometry be performed by e.g. a mechanical drive device is connected to the reference mirror 10 to move it in the direction of the optical axis 89.
  • a mechanical drive device is connected to the reference mirror 10 to move it in the direction of the optical axis 89.
  • the Linnik interferometer 4 has a central beam splitter arrangement 24, which is arranged such that at least the observation device 15 and a unit 14 comprising an objective 8 and the reference mirror 10 are arranged on one and the same side of the measuring head. This opens the way to integrate the Linnik interferometer into a measuring machine. This results in a vibration-resistant, robust and space-saving arrangement.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

L'invention concerne un interféromètre de Linnik compact (4) comprenant un agencement central (24) de séparation de faisceaux conçu de sorte qu'au moins une unité d'observation (15), une unité d'éclairage (20) et une unité (14) comprenant un objectif (8) et un miroir de référence (10) soient agencés du même côté que la tête de mesure, ce qui permet d'intégrer cet interféromètre dans une machine de mesure. L'invention permet ainsi d'obtenir un agencement robuste, peu encombrant et insensible aux vibrations.
PCT/EP2008/008906 2007-11-08 2008-10-22 Interféromètre de linnik compact Ceased WO2009059693A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200710053124 DE102007053124B3 (de) 2007-11-08 2007-11-08 Kompaktes Linnik-Interferometer
DE102007053124.0 2007-11-08

Publications (1)

Publication Number Publication Date
WO2009059693A1 true WO2009059693A1 (fr) 2009-05-14

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2008/008906 Ceased WO2009059693A1 (fr) 2007-11-08 2008-10-22 Interféromètre de linnik compact

Country Status (2)

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DE (1) DE102007053124B3 (fr)
WO (1) WO2009059693A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010056122B3 (de) * 2010-12-20 2012-06-28 Universität Stuttgart Verfahren zur robusten, insbesondere weitskaligen Interferometrie

Citations (5)

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Publication number Priority date Publication date Assignee Title
GB1301626A (fr) * 1970-06-29 1973-01-04
US5493394A (en) * 1994-05-25 1996-02-20 The Boeing Company Method and apparatus for use in measuring frequency difference between light signals
US20040179202A1 (en) * 2003-03-13 2004-09-16 Abdurrahman Sezginer Scatterometry by phase sensitive reflectometer
WO2007002898A2 (fr) * 2005-06-29 2007-01-04 University Of South Florida Balayage tomographique variable avec holographie interferentielle numerique a balayage en longueur d'onde
DE102006015387A1 (de) * 2006-04-03 2007-10-04 Robert Bosch Gmbh Interferometrische Messvorrichtung

Family Cites Families (7)

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US4818110A (en) * 1986-05-06 1989-04-04 Kla Instruments Corporation Method and apparatus of using a two beam interference microscope for inspection of integrated circuits and the like
US5398113A (en) * 1993-02-08 1995-03-14 Zygo Corporation Method and apparatus for surface topography measurement by spatial-frequency analysis of interferograms
US6172349B1 (en) * 1997-03-31 2001-01-09 Kla-Tencor Corporation Autofocusing apparatus and method for high resolution microscope system
US6624894B2 (en) * 2001-06-25 2003-09-23 Veeco Instruments Inc. Scanning interferometry with reference signal
DE10256273B3 (de) * 2002-12-03 2004-03-18 Carl Mahr Holding Gmbh Interferenzoptische Formmesseinrichtung mit Phasenschiebung
DE102004022341A1 (de) * 2004-05-04 2005-12-29 Carl Mahr Holding Gmbh Vorrichtung und Verfahren zur kombinierten interferometrischen und abbildungsbasierten Geometrieerfassung insbesondere in der Mikrosystemtechnik
DE102004025290A1 (de) * 2004-05-19 2005-12-22 Carl Mahr Holding Gmbh Verfahren und Vorrichtung zur optischen Erfassung von Abstandsänderungen

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1301626A (fr) * 1970-06-29 1973-01-04
US5493394A (en) * 1994-05-25 1996-02-20 The Boeing Company Method and apparatus for use in measuring frequency difference between light signals
US20040179202A1 (en) * 2003-03-13 2004-09-16 Abdurrahman Sezginer Scatterometry by phase sensitive reflectometer
WO2007002898A2 (fr) * 2005-06-29 2007-01-04 University Of South Florida Balayage tomographique variable avec holographie interferentielle numerique a balayage en longueur d'onde
DE102006015387A1 (de) * 2006-04-03 2007-10-04 Robert Bosch Gmbh Interferometrische Messvorrichtung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
S. FRANZ, R. WINDECKER, H.J. TIZIANI: "Machine-tool-embedded white light interferometrical sensor for diameter measurements", PROCEEDINGS OF SPIE, vol. 5144, 13 February 2004 (2004-02-13), pages 484 - 491, XP002507893, Retrieved from the Internet <URL:http://dx.doi.org/10.1117/12.501072> *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010056122B3 (de) * 2010-12-20 2012-06-28 Universität Stuttgart Verfahren zur robusten, insbesondere weitskaligen Interferometrie

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